Optical transceivers with closed-loop digital diagnostics

ABSTRACT

Systems and methods for performing closed-loop diagnostics in optical transceiver. The TOSA of an optical receiver includes a primary transmit module and a secondary receiver module. The transmit module transmits a data signal to a ROSA of another optical transceiver. The ROSA has a secondary transmit module that can transmit a diagnostic data signal back to the secondary receiver module of the TOSA. The TOSA can use the diagnostic data received from the ROSA to automatically adjust itself and perform closed-loop feedback functions. The closed loop diagnostics can be implemented in a network where one transceiver may be connected with more than one other transceiver in a multi-node configuration.

THE FIELD OF THE INVENTION

The present invention relates generally to the field of opticaltransceivers. More particularly, embodiments of the invention relate tooptical transceivers with closed-loop diagnostics.

BACKGROUND OF THE INVENTION

High speed data communication networks often use optical transceivers totransmit and receive optical signals carrying digitally encoded data.Optical transceivers typically use an optical transmitter, such as alaser, to transmit optical signals and an optical receiver, such as aphotodiode, to receive optical signals. Conventional transceiversrequire a pair of optical fibers to implement full-duplex functionality.One optical fiber connects with the optical transmitter while the otheroptical fiber connects with the optical receiver.

Advancements in optical data communication technology have enabledbidirectional data transmission over a single optical fiber. Thesebidirectional communication systems can allow for data to be transmittedin both directions over a single optical fiber instead of requiring anindividual optical fiber for each direction of data transmission.Bidirectional communication technology increases bandwidth byessentially doubling the data payload capacity. While bidirectionalcommunication in optical networks can increase the amount of informationthat can be transmitted and received, these networks may still beaffected by data transmission errors. Such errors can be caused, forexample, by improper laser driver power control or modulation.

Diagnostic information is often used to address these types of problems.However, conventional diagnostic functions are open-loop in nature. Forexample, an optical transmitter can report its own output power and anoptical receiver can report its own received optical power. While theoptical transmitter or the optical receiver can provide usefuldiagnostic information, the diagnostic information may not be at thelocation best suited to utilize the information and implement acorrection procedure because of the open-loop nature of the system. Forexample, an optical receiver that reports low optical power cannot beused by the optical transmitter that transmitted the optical signal. Inother words, human intervention is typically needed to fix any problemsindicated by the diagnostic information provided by the opticaltransmitter or the optical receiver. Further, conventional opticaltransceivers cannot self-compensate to maintain the integrity of theoptical data when the data link degrades.

BRIEF SUMMARY OF THE INVENTION

These and other limitations are overcome by embodiments of the presentinvention, which relate to systems and methods for closed loopdiagnostics in an optical environment. Embodiments of the inventionrelate to self adjusting optical transceivers with closed loopdiagnostics. Advantageously, a self adjusting optical transceiverenables high speed bidirectional communications in an optical networkthat can perform closed-loop feedback functions.

An exemplary embodiment of the invention provides an optical transceivermodule that automatically adjusts to maintain an integrity of a datalink. The optical transceiver can include a ‘transmit’ opticalsubassembly (“TOSA”) and a ‘receive’ optical subassembly (“ROSA”).Accordingly, the TOSA can include a primary transmitter module, asecondary receiver module, and a first diagnostic module. The primarytransmitter module can be configured for transmitting a first datasignal through an optical fiber. Also, the secondary receiver module canbe configured for receiving a second data signal through the sameoptical fiber. The first diagnostic module can be communicativelycoupled with both the transmitting subassembly and the receivingsubassembly. Additionally, the first diagnostic module can be configuredto use at least a portion of the second data signal to adjust at leastone of a power and a modulation of the first data signal. The seconddata signal may also be used to adjust the wavelength of the laser whenthe laser is tunable.

In another embodiment, the ROSA can include a primary receiver module, asecondary transmitter module, and a second diagnostic module. Theprimary receiver module can be configured for receiving a third datasignal through a second optical fiber. Also, the secondary transmittermodule can be configured for transmitting a fourth data signal throughthe second optical fiber. The second diagnostic module can becommunicatively coupled with the receiver module and the transmittermodule. Additionally, the second diagnostic module can be configured forusing at least a portion of the third data signal to generate at least aportion of the fourth data signal, the at least a portion of the fourthdata signal containing diagnostic data about the first data signal. Oneof skill in the art can appreciate that the first and second diagnosticmodules can be embodied as a single diagnostic module that is used, whennecessary by both the ROSA and/or the TOSA.

These and other exemplary embodiments of the present invention willbecome more fully apparent from the following detailed description andappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

To further clarify the above and other advantages and features of thepresent invention, a more particular description of the invention willbe rendered by reference to specific embodiments thereof which areillustrated in the appended drawings. It is appreciated that thesedrawings depict only typical embodiments of the invention and aretherefore not to be considered limiting of its scope. The invention willbe described and explained with additional specificity and detailthrough the use of the accompanying drawings in which:

FIG. 1 is a schematic diagram that illustrates aspects of an exemplaryembodiment of a duplex bidirectional transceiver system;

FIG. 2 is a schematic diagram that illustrates aspects of an exemplaryembodiment of duplex bidirectional transceiver assemblies within aduplex bidirectional communication system;

FIG. 3 is a schematic diagram that illustrates an embodiment of abidirectional transceiver module operable within a duplex bidirectionalcommunication system;

FIG. 4 is a schematic diagram that illustrates an embodiment ofbidirectional transceiver modules operable in a bidirectionalcommunication system; and

FIG. 5 is a flow diagram that illustrates some aspects of an exemplarymethod operable with a duplex bidirectional communication system.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The present invention relates to optical transceivers with closed-loopdiagnostic functions. The systems and methods of the present inventionenable diagnostic information to form a closed-loop between opticaltransceivers. The closed-loop enables, for example, an opticaltransceiver that receives an optical signal to transmit diagnosticinformation back to the transmitting optical transceiver. Embodiments ofthe invention enable closed-loop diagnostics without reducing theeffective bandwidth of the data link between the optical transceivers.Embodiments of the invention also accommodate network architectureswhere, for example, multiple transceivers are included in the data linkand a particular transceiver is connected with at least two othertransceivers.

Reference will now be made to the drawings to describe various aspectsof the exemplary embodiments of the invention. The drawings arediagrammatic and schematic representations of exemplary embodiments, andare not limiting of the present invention.

Operating Environment

While the exemplary embodiments of the invention discussed below areusable in conjunction with a high speed optical data transmission systemconforming to the small form factor pluggable (SFP) standards or to becompatible with gigabit interface connectors (GBIC), such operatingenvironments are exemplary only and embodiments of the invention can beemployed in any of a variety of current and future high speed datatransmission systems. Additionally, the invention can be operable withGigabit Ethernet (GigE) and/or Fibre Channel and/or SONET compliantsystems.

FIG. 1 is a schematic diagram that illustrates an exemplary embodimentof a bidirectional optical data communication system 100 in accordancewith the present invention. FIG. 1 illustrates transceiver modules 101,108 that are similarly configured, and are connected with the opticalfibers 110, 111 and thus form an optical link. As described herein, theoptical fibers 110, 111 are each a single fiber, however, multipleoptical fibers can be utilized to link the transceiver modules 101, 108when appropriate. Each transceiver module 101, 108 includes a ‘transmit’optical subassembly (“TOSA”) 102, 146 and a ‘receive’ opticalsubassembly (“ROSA”) 118, 140.

In this example, the optical signal generated by each TOSA 102, 146 isreceived by a corresponding ROSA 118, 140 through the optical fibers110, 111. The optical fibers 110, 111 can include new or legacy fibers,and some exemplary embodiments of the present invention can beimplemented without necessitating any change in existing optical fibersand/or connectors.

Each TOSA 102, 146 includes a transmitter module 104, 148, and areceiver module 106, 150. Each ROSA 118, 140 similarly includes atransmitter module 122, 144 and a receiver module 120, 142. By using thetransmitter modules 104, 122, 144, 148 and receiver modules 106, 120,142, 150, the transceiver modules 101, 108 can perform bidirectionalcommunication over each of the optical fibers 110, 111. Thus the TOSA102 and the ROSA 118 can communicate bidirectionally over the opticalfiber 110. The ROSA 140 and the TOSA 146 can similarly communicatebidirectionally over the optical fiber 111.

In one embodiment, the communication links between the transmittermodules 104, 148 and the receiver modules 120, 142 can transmit datapayloads 114, 115 over the optical fibers 110, 11. Accordingly, thetransmitter modules 104, 148 can be designated as primary transmittermodules 104, 148. Correspondingly, the receiver modules 120, 142 can bedesignated as primary receiver modules 120, 142.

Also, the communication link between the transmitter modules 122, 144and the receiver modules 106, 150 can transmit diagnostic data signals116, 117 over the optical fiber 110, 111. As such, the transmittermodules 122, 144 can be designated as secondary transmitter modules 122,144. Correspondingly, the receiver modules 106, 150 can be designated assecondary receiver modules 106, 150.

The inclusion of transmitters in a ROSA and receivers in a TOSA allowsfor both the ROSA and the TOSA to each transmit and receive data.Accordingly, the transmitters in the TOSA can be considered primary andthe receivers within the TOSA can be considered secondary because theTOSA transmitters are primarily transmitting the data payload and theTOSA receivers are performing a secondary function of receivingdiagnostic data about that data payload. Similarly, the receivers in theROSA can be considered primary and the transmitters within the ROSA canbe considered secondary because the ROSA receivers are primarilyreceiving the data payload and the ROSA transmitters are transmittingdiagnostic information about the optical quality of the received datapayload back to the originating TOSA. This can be useful because theinformation received by a ROSA may have an inadequate optical quality,and providing the ROSA with the transmission capability can allow fordiagnostic data pertaining to the inadequate optical quality to betransmitted back to the originating TOSA. Accordingly, the TOSA can thenadjust the transmission to improve the optical quality received at theROSA.

With continuing reference to FIG. 1, the transceivers 101, 108 can eachimplement closed-loop digital diagnostics and transfer diagnostic data116, 117 from each ROSA 118, 140 back to its corresponding TOSA 102, 146using the secondary transmitter 122, 144 and secondary receiver modules106, 150. The optical fibers 110, 111 can carry data payloads 114, 115and diagnostic data 116, 117 in both directions across the opticalfiber.

One advantage of the present invention, in comparison to conventionalbidirectional systems is that the diagnostic data transmitted, forexample, by the secondary transmitter modules 122, 144 does not consumeany of the bandwidth available to the primary transmitter modules 104,148. This is because the primary and secondary transmitters thattransmit signals over the same optical fiber can propagate the data atdifferent wavelengths.

Referring now to FIG. 2, details are provided concerning the generalarchitecture of an exemplary embodiment of the present invention thatincludes a multi-node communication system 200. Such a multi-nodecommunication system 200 can include multiple independent transceivers201, 220, 240. Each transceiver 201, 220, 240 includes a TOSA 202, 222,250 and a ROSA 208, 230, 242. Accordingly, the TOSA 202 is incommunication with the ROSA 242 over optical fiber 211, the TOSA 222 isin communication with the ROSA 208 over optical fiber 213, and the TOSA250 is in communication with the ROSA 230 over optical fiber 215.

Additionally, each TOSA 202, 222, 250 includes a transmitter module 204,226, 252 and a receiver module 206, 224, 254. The transmitter modulesand receiver modules of the transceivers 201, 220, 240 can be eitherprimary or secondary modules as described previously with respect toFIG. 1.

An advantage of the present inventive multi-node communication system200 allows for closed-loop digital diagnostics between twocommunicatively coupled transceivers within a multi-node communicationsystem over a single optical fiber. For example, the TOSA 202 cancommunicate with the ROSA 242. As such, the TOSA 202 can transmit a datapayload 217 over optical fiber 211 to the ROSA 242, and the ROSA 242 cantransmit diagnostic data 223 pertaining to the signal quality of thedata payload 217 back to the originating TOSA 202 over the same opticalfiber 211.

This multi-node communication system configuration allows for a ROSA toanalyze the optical quality of the data payload sent by a TOSA, and thentransmit diagnostic information back to the TOSA so that the datapayload signal can be adjusted to improve the optical quality. Thus,closed-loop feedback control can be implemented between each TOSA andROSA within a multi-node network to improve the quality of the datapayload signals. Additionally, the multi-node communication system caninclude a plurality of transceivers where each TOSA and ROSAcommunication linked together over a single optical fiber, asexemplified by TOSA 202 and ROSA 242, can implement the closed-loopfeedback control. Also, is should be appreciated that a multi-nodecommunication system can include more than just three nodes asexemplified.

Structure

With reference now to FIG. 3, another exemplary embodiment of thepresent invention includes details of bidirectional opticalcommunication between a two-node pair 300, although one of skill in theart can appreciate that the embodiments of the invention can beimplemented in a multimode system as well. Such an embodiment caninclude first and second transceiver modules 302, 350, which can beidentical modules, each having a pair of bidirectional subassemblies.The first transceiver module 302 includes a bidirectional TOSA 304 and abidirectional ROSA 328. Also, the second transceiver module 350 includesa bidirectional ROSA 352 and a bidirectional TOSA 380. Each of thebidirectional subassemblies in the first transceiver module 302 are incommunication with their corresponding bidirectional subassemblies inthe second transceiver module 350 through the optical fibers 311, 313.

Each of the bidirectional subassemblies within the transceivers 302, 350can include various modules. As such, the TOSA 304 includes a primarytransmitter module (PTxM) 312 and a secondary receiver module (SRxM)314, and the ROSA 352 includes a primary receiver module (PRxM) 356 anda secondary transmitter module (STxM) 360. Also, the ROSA 328 includes aprimary receiver module (PRxM) 332 and a secondary transmitter module(STxM) 330, and the TOSA 380 includes a primary transmitter module(PTxM) 388 and a secondary receiver module (SRxM) 382. These modules areconfigured to be in communication with their counterparts in thebidirectional system through optical fibers 311, 313.

The transmitter modules can be configured to provide differentwavelengths. For example without limitation, the TOSA 304 PTxM 312 canbe a 1550 nanometer (nm) distributed feedback (DFB) laser, therebyproviding a first wavelength data transmission (λ₁) to communicate thedata payload 315. On the other hand, the ROSA 352 STxM 360 can be, alsoby way of example only, a 1310 nm Fabry Perot (FP) laser, therebyproviding a second wavelength data transmission (λ₂) to communicate thediagnostic data 319. Thus, the first and second wavelength datatransmissions for the payload data (λ₁) and diagnostic data (λ₂) can bepropagated over the same optical fibers in opposite directions.Additionally, the receiver module can include photodetector, such as aphotodiode to detect the incoming data signals.

With respect to the TOSA 304 and the ROSA 352 communicative pair, thePTxM 312 is communicatively coupled to a first end of an optical fiber311 through a beam splitter 316 and the PRxM 356 is communicativelycoupled to a second end of the optical fiber 311 through another beamsplitter 354. As such, the PTxM 312 can transmit a data payload 315 tothe PRxM 356 over the optical fiber 311. Additionally, the STxM 360 iscommunicatively coupled to the second end of the optical fiber 311through the beam splitter 354, and the SRxM 314 is communicativelycoupled to the first end of optical fiber 311 through the beam splitter316, where the STxM 360 can transmit diagnostic data 319 to the SRxM314.

In accordance with the present invention, the beam splitters of the TOSAand the ROSA can be similar and even configured to be identical whenappropriate. The beam splitters can be configured to separate twodifferent wavelengths transmitted from the TOSA and from the ROSAbecause both optical signals will pass through each beam splitter at theTOSA and the ROSA. The beam splitter can receive a signal from atransmitter module at a first wavelength (λ₁) and route the signal intothe optical fiber. From the opposite direction, the beam splitter canalso receive a second signal at a second wavelength (λ₂) from the sameoptical fiber. The beam splitter then reflects the second signal at thesecond wavelength (λ₂) towards the receiver module. Accordingly, theTOSA beam splitter can transmit λ₁ and reflect λ₂, while the ROSA beamsplitter can transmit λ₂ and reflect λ₁. For example without limitation,the exemplary transmitter wavelengths of approximately 1310 nm for thesecondary transmitter and 1550 nm for the primary transmitter can bedistinguished with a beam splitter having high reflectivity for eitherthe 1310 nm or 1550 nm wavelength bands and a high transmission for theother wavelength. One of skill in the art can appreciate that otherwavelengths can be used to implement the closed loop diagnostics.

In an alternative embodiment of the present invention, the bidirectionaloptical data communication system described herein does not require theprimary transmitters that transmit the data payload and secondarytransmitters that transmit the diagnostic data to transmit significantlydifferent wavelengths. Each transceiver module can include an echocancellation device configured to remove the crosstalk and/or reflectedtransmission optical signals that are not intended to be received by thereceiver. For example, when some portion of the payload data signal isreflected back into the transceiver, an echo cancellation device canextinguish the payload data signal from the diagnostic data signal so asto prevent the diagnostic data signal from being corrupted by reflectedsignals. In one aspect, the echo cancellation device can be part of thebeam splitters.

With continuing reference to FIG. 3, while the PTxM 312 iscommunicatively coupled to the beam splitter 316 the beam splitter 316,is also communicatively coupled to the SRxM 314. This can allow opticaldata received into the beam splitter 316 from the optical fiber 311 topass to the SRxM 314. Additionally, the SRxM 314 is communicativelycoupled to a diagnostic module 322, which in turn is thencommunicatively coupled to the PTxM 312. This can allow the SRxM 314 totransfer diagnostic data to the diagnostic module 322 so thattransmission control parameters can be transferred to the PTxM 312 forimproving the quality of the data payload signal. Thus, the TOSA 304 canself-adjust the optical data transmission signal by using the receiveddiagnostic data.

Additionally, with a more specific reference to ROSA 352, the beamsplitter 354 is configured to receive the data payload 315 from theoptical fiber 311, and transfer the data payload 315 to the PRxM 356.The PRxM 356 is also communicatively coupled to a diagnostic module 358,which in turn is communicatively coupled to the STxM 360. This enablesthe PRxM 356 to transfer information pertaining to the incoming datapayload 315 or a portion of the data payload to the diagnostic module358, where the diagnostic module can then analyze the quality of thedata payload 315 to determine whether the quality is adequate or needsimprovement. As such, the diagnostic module 358 can then generatediagnostic data 319 pertaining to the quality of the data payload 315signal, which can then be transferred to the STxM 360. The STxM 360 isconfigured to transmit the diagnostic data 319 to the beam splitter 354,which routes the diagnostic data 319 into the optical fiber 311 fortransmission to the corresponding TOSA 304.

Since the transceiver modules 302, 350 are substantially identical, withthe TOSA 304 communicating with the ROSA 352 being substantiallyidentical to the TOSA 380 communicating with the ROSA 328, the TOSA 380and the ROSA 328 operate as described above. In other words, the ROSA328 functions similarly to the ROSA 352 and the TOSA 380 functionssimilarly to the TOSA 304.

An exemplary embodiment of the present invention can include thetransceiver modules 302, 350 to be each coupled with a host computingsystem (“host”) (not shown). The TOSA 304, 380 and the ROSA 352, 328 canbe coupled to a host via any of the subassemblies.

In another embodiment, the optical transceiver of the instant inventioncan include additional components. Some of the additional componentsthat can be included within a receiving aspect of the transceiver caninclude transimpedence amplifiers, post-amplifiers, detector and loss ofsignal detectors for processing the data signal that is received intothe receiver module. Additionally, the transmitter module can include alaser, laser driver, laser driver power controller, monitor, andauto-shutdown controller. The receiver module and transmitter modulecomponents can be controlled with a control module that can adjustsettings of the transceiver.

Referring now to FIG. 4, a detailed exemplary embodiment of the presentinvention includes a TOSA 402 in communication with a ROSA 404. The TOSA402 and the ROSA 404 are configured to communicate via an optical fiber110, where the TOSA 402 sends a data payload 114 to the ROSA 404 and theROSA sends diagnostic data 116 to the TOSA 402. Accordingly, both theTOSA 402 and the ROSA 404 include components to enable bidirectionalcommunication over the single optical fiber 110. In one aspect, the TOSA402 and the ROSA 404 can each be independently coupled with a host.

The TOSA 402 can be configured to receive data input from the host intoa laser driver 412, where the data received into the laser driver 412 isconverted into signals to be emitted from a laser 414 as a data payload114 optical signal. One such data input received into the laser driver412 can be a transmission disablement input (TxDIS) that disables thedata transmission from the laser driver 412 to the laser 414.

Within the TOSA 402, a laser driver power controller 423 is coupled withand regulates the laser driver 412. Also, the laser driver 412 iscommunicatively coupled with the laser 414 so that the laser driver 412can provide power and modulation parameters to the laser 414 to controlthe optical data signal transmission characteristics.

The laser 414 emits light carrying the optical data to a beam splitter416, where at least a portion of the laser light can be transferred to alaser monitor 426 to determine the characteristics of the lasertransmission power and/or modulation. The beam splitter 416 then routesthe optical data signal into the optical fiber 110 to transmit the datapayload 114 to the ROSA 404.

The laser monitor 426 receives and analyzes the laser transmission powerand/or modulation in order to provide the laser driver 412 withinstructions for adjustments to correct the laser transmissioncharacteristics. As such, the laser monitor 426 transfers theinformation pertaining to the laser transmission to the laser driverpower controller 423 and an auto-shutdown controller 422. The laserpower controller 423 is configured to provide the laser driver 412 withpower and/or modulation adjustments so that the laser 414 can emit asignal with improved quality. As such, the monitor 426, laser powercontroller 423, and auto-shutdown controller 422 can adjust the qualityof the optical signal through an internal control mechanism and/orprocedure within the TOSA 402.

Additionally, the auto-shutdown controller 422 is communicativelycoupled with the laser driver 412 so that when the laser monitor 426indicates that the laser transmission should be shut down, the laserdriver 412 can cease transferring data to the laser 414. In anotheraspect, the auto-shutdown controller 422 can be communicatively coupledwith an auto-shutdown assembly 424, where this redundant communicationsystem can allow for the auto-shutdown controller 422 to sever the dataconnection to the laser 414. This optional aspect can be implementedwhen the laser driver 412 does not respond to the auto-shutdowncontroller 422.

The beam splitter 416 is coupled to the optical fiber 110 so as totransmit the data payload 114 and to receive the diagnostic data 116sent from the ROSA 404. The beam splitter 416 is also communicativelycoupled to detector 418 to communicate the diagnostic data 116 receivedfrom the ROSA 404 to the detector 418. After the detector 418 receivesthe diagnostic data 116 from the beam splitter 416, the opticaldiagnostic data 116 is typically converted to a corresponding electricaldata signal. Also, the detector 418 is communicatively coupled to areceiver 420 so that the electrical diagnostic data can be transferredto the receiver 420.

When the receiver 420 obtains the diagnostic data, the data can beprocessed and/or analyzed for power and/or modulation parameters, whichcan include the power and/or modulation parameter of either thetransmission signal emitted by the TOSA 402 or ROSA 404. Also, thereceiver 420 can be coupled to a loss of signal detector (“LOS”) 409,which can detect the signal power and associated current or voltageparameters to determine whether the received diagnostic data signal issufficiently powerful. The receiver 420 can be configured to have morethan one output, which can transfer the received diagnostic data to ahost or to a diagnostic module 430 or directly to the laser driver 412.

The diagnostic module 430 can be configured to receive the diagnosticdata for processing and/or analysis to determine whether any of thelaser transmission parameters could be adjusted to provide a bettersignal at the receiving ROSA 404. Such laser transmission parameters caninclude, without limitation, laser power and/or modulation. For example,the diagnostic module 430 can interpret the diagnostic data to determinewhether the laser power at the receiving transceiver is inadequate, andthen implement a power increase command. Accordingly, the diagnosticmodule 430 can send the power increase command to the laser driver powercontroller 423 or to the laser driver 412 to increase the power of thelaser 414.

For example, the diagnostic module 430 can interpret the diagnostic datato indicate that the laser modulation is improper and the signal beingreceived by the ROSA 404 is unacceptable or unreadable. The diagnosticmodule 430 can then implement a modulation adjustment command and sendthe command to the laser driver 412 to adjust the laser modulation. Ofcourse other laser adjustments can be made in accordance with thetransmission signal characteristics received by the ROSA 404, and any ofthe TOSA 402 components can be configured to make the proper adjustmentsto obtain an adequate data transmission signal.

In another embodiment, the ROSA 404 is configured to receive the payloaddata 114 transmitted from the TOSA 402 via the optical fiber 110 andtransmit the diagnostic data 116 over the same optical fiber 110. Theoptical fiber 110 is coupled to a beam splitter 417 which routes thepayload data 114 to a detector 419. The beam splitter 417 iscommunicatively coupled with the detector 419 so that the receivedoptical data payload 114 can be converted to electrical data for furtherprocessing and distribution. The beam splitter 417 is alsocommunicatively coupled to a laser 415.

The detector 419 is also communicatively coupled with the receiver 421so that the data received into the ROSA 404 can be transferred to thereceiver 421. The receiver 421 can process and/or analyze the receiveddata, and transfer the data payload to the host computing system. Also,the receiver can be communicatively coupled to a loss of signal detector(LOS) 407. The receiver 421 can be configured to have more than oneoutput, which can transfer the received data to a host or to adiagnostic module 431 or directly to the laser driver 413.

The diagnostic module 431 is configured to receive data from thereceiver 421 for processing and/or analysis of the data payload 116 todetermine whether any of the TOSA 402 laser transmission parameterscould be adjusted in order to provide better signal quality at the ROSA404. The laser transmission parameters can include, without limitation,laser power and/or modulation. For example, the diagnostic module 431can analyze the data payload signal and determine the laser power beingreceived into the ROSA 404 to be inadequate, and then generatediagnostic data for instructing the TOSA 402 to implement a powerincrease command. Alternatively, the closed-loop diagnostics can be usedto lower the laser power of the TOSA 402 if the ROSA 404 is beingsaturated.

The diagnostic module 431 then sends the diagnostic data to a laserdriver power controller 427 or to a laser driver 413 for transmissionback to the TOSA 402. Accordingly, the laser power controller 427 and/orthe laser driver 413 can direct the laser 415 to transmit an opticalsignal carrying the diagnostic data to the TOSA 402, where a laser 415emits light into the beam splitter 417 which is then routed into theoptical fiber 110.

Additionally, a monitor 429 can receive some of the optical data signalfrom the laser 415 to determine the characteristics of the diagnosticlaser transmission power and/or modulation. The monitor 429 can analyzethe laser transmission power and/or modulation in order to provide thelaser driver 413 with adjustments to correct the laser transmission. Assuch, the monitor is configured to transfer the information pertainingto the laser transmission to the laser driver power controller 427 andthe auto-shutdown controller 428.

The laser power controller 427 is configured to provide the laser driver413 with power and/or modulation adjustments so that the laser 415 canemit an improved signal from the ROSA 404. Also, the auto-shutdowncontroller 428 can be communicatively coupled with the laser driver 413to terminate transmission of the diagnostic data signal when the monitorindicates that the laser should be shut down. Additionally, theauto-shutdown controller 428 can be communicatively coupled with thediagnostic auto-shutdown assembly 425 to provide a redundant system toterminate the transmission of the diagnostic data when the laser driver413 does not respond to the auto-shutdown controller 428.

In another embodiment of the present invention, the ROSA 404 can beconfigured to receive data input from the host into the laser driver413, where the data received into the laser driver 413 from the host isconverted into signals to be emitted from the laser 415. Such data canbe carried through the optical fiber 110 along with the diagnostic datasignal. Accordingly, the ROSA 404 can be configured to transmit a datapayload along with the diagnostic data 116 to the TOSA 402. Thus, thelaser driver 413 can have more than one input from the host, which caninclude a transmission disablement input (TxDIS) and data payloadinputs.

In another exemplary embodiment of the present invention, the TOSAdiagnostic modules, shown in FIGS. 3 and 4 that primarily serve toprovide the laser with adjustment commands to adjust the laser signal inorder to provide the corresponding ROSA with an adequate data signal,are optional. Accordingly, these diagnostic modules can be incorporatedinto the primary transmitter modules or the secondary receiver modulesof FIG. 3 and any of the TOSA components of FIG. 4. Thus, thesediagnostic modules can be incorporated into any part of the TOSA so longas the laser transmission characteristics are adjustable at the TOSA inorder to provide the ROSA with an adequate data signal. For example,with reference back to FIG. 3, the diagnostic module 322 of the TOSA 304can be incorporated into the secondary receiver module 314. As such, thereceiver module 314 can instruct the transmitter module to change thelaser transmission characteristics in accordance with the signal qualityneeds at the corresponding ROSA 352.

Similarly, another exemplary embodiment of the present inventionprovides for the ROSA diagnostic modules shown in FIGS. 3 and 4 thatprimarily serve to generate diagnostic data about the quality of thepayload data received into the ROSA to be optional. As such, thesediagnostic modules can be incorporated into the primary receiver modulesor secondary transmitter modules of FIG. 3, and any of the ROSAcomponents in FIG. 4 so long as the ROSA is capable of generatingdiagnostic data for closed-loop feedback control of the transmittedsignal.

In another aspect, the optical signal transmitting components (e.g.,laser or light emitting diode) used in the secondary transmitter thattransmits the diagnostic data back to the originating transceiver can beof lower quality than the originating primary transmitter. Thediagnostic data does not require as much bandwidth as the primarytransmitter, for example. Also, the secondary optical signal receivingcomponents such as a photodiode can be of lower quality than the primaryreceiver. Accordingly, manufacturing rejects for primary transmittersand primary receivers can be adequately used as secondary transmittersand secondary receivers, which can decrease overall costs.

Methods of Operation

In practicing the invention, the transceiver modules, components, andsubcomponents can be operable in a closed-loop feedback controlledbidirectional optical data network system. The system can be configuredto bidirectionally transmit and receive data over a single opticalfiber. A transceiver having a transmit port and a receive port cantransmit bidirectionally over two fibers. In such a system, methods canbe implemented for closed-loop feedback control of the TOSA lasertransmission characteristics. Accordingly, an optical transceiver modulecan automatically adjust, for example, the power and/or modulation of atransmitted signal to maintain the integrity of a data link.

With reference to FIG. 5, an exemplary embodiment of the presentinvention provides a method 500 for implementing closed-loop feedbackcontrol of the laser transmission between two or more transceivermodules, each including a TOSA and a ROSA. Accordingly, the TOSA of atransceiver transmits a data signal to the ROSA of another transceiver(stage 502). As such, the ROSA receives the data signal sent from theTOSA (stage 504). After the data signal has been received into the ROSA,diagnostic data pertaining to the data signal is generated (stage 506)in the ROSA. The diagnostic data can be generated to identify theadequacy or inadequacy of the data signal at the site of reception.Thus, the diagnostic data can indicate whether the transmission needs tobe increased in power or whether the modulation characteristics needadjusting.

The diagnostic data is then transmitted from the ROSA (stage 508), whichis then received into the originating TOSA (stage 510). The TOSA canthen determine whether the diagnostic data indicates whether thetransmission characteristics are adequate or inadequate (stage 512).When the diagnostic data indicates the data signal received into theROSA is adequate, the TOSA can continue transmission without adjustingthe characteristics of the laser (stage 514). On the other hand, whenthe diagnostic data indicates that the transmission characteristics areinadequate when received into the ROSA, the TOSA can adjust theappropriate laser transmission characteristics (stage 516), such aspower and/or modulation.

In another exemplary embodiment of the present invention, a method forimplementing closed-closed loop digital diagnostics can operatecontinuously. While the TOSA is transmitting a data payload to the ROSA,the ROSA can simultaneously transmit diagnostic data back to theoriginating TOSA. This can provide continuous adjustments in order tomaintain a high quality for the signals being transmitted.

With respect to the aspect of generating diagnostic data, the generationcan be by any process and utilize any portion of the data payload thatresults in diagnostic data pertaining to the data payload. Thediagnostic data allows the transceiver originating the data payload toalter the power and/or modulation of the transmission signal to improvethe data signal characteristics at the receiving transceiver. Suchdiagnostic data generation can include; taking a portion of the datasignal and transferring it back to the originating transceiver;processing the data signal through an algorithm to obtain informationabout the signal; measuring signal parameters and transferring theparameters back to originating transceiver; and/or creating data thatindicates the adequacy or inadequacy of the signal characteristics.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

1. A an optical transceiver module that automatically adjusts tomaintain an integrity of a data link, the optical transceivercomprising: a ‘transmit’ optical subassembly (“TOSA”) having: a primarytransmitter module for transmitting a first data signal through a firstoptical fiber; a secondary receiver module included with the primarytransmitter module for receiving a second data signal through the firstoptical fiber; and a first diagnostic module communicatively coupledwith the primary transmitter module and the secondary receiver module,the first diagnostic module using at least a portion of the second datasignal to adjust at least one of a power, a modulation and a wavelengthof the first data signal; and a ‘receive’ optical subassembly (“ROSA”)having: a primary receiver module for receiving a third data signalthrough a second optical fiber; a secondary transmitter module includedwith the primary receiver module for transmitting a fourth data signalthrough the second optical fiber; and a second diagnostic modulecommunicatively coupled with the primary receiver module and thesecondary transmitter module, the second diagnostic module using atleast a portion of the third data signal to generate at least a portionof the fourth data signal, the at least a portion of the fourth datasignal containing diagnostic data about the first data signal.
 2. Anoptical transceiver module according to claim 1, wherein the primarytransmitter module includes a laser configured to emit the first datasignal at a first wavelength.
 3. An optical transceiver module accordingto claim 2, wherein the secondary receiver module includes a photodiodeconfigured to receive the second data signal at a second wavelength. 4.An optical transceiver module according to claim 3, further comprising afirst beam splitter communicatively coupled to with the primarytransmitter module, the secondary receiver module, and the first opticalfiber, the first beam splitter being configured to separate the firstwavelength from the second wavelength.
 5. An optical transceiver moduleaccording to claim 4, wherein the primary receiver module includes aphotodiode configured to receive the third data signal at a thirdwavelength.
 6. An optical transceiver module according to claim 5,wherein the secondary transmitter module includes a laser configured toemit the fourth data signal at a fourth wavelength.
 7. An opticaltransceiver module according to claim 6, further comprising a secondbeam splitter communicatively coupled to with the primary receivermodule, the secondary transmitter module, and the second optical fiber,the second beam splitter being configured to separate the thirdwavelength from the fourth wavelength.
 8. An optical transceiver moduleaccording to claim 7, wherein the first wavelength is substantially thesame as the third wavelength.
 9. An optical transceiver module accordingto claim 8, wherein the second wavelength is substantially the same asthe fourth wavelength.
 10. An optical transceiver module according toclaim 8, wherein at least one of the first diagnostic module and thesecond diagnostic module is integrated into the control module.
 11. Anoptical transceiver module according to claim 1, further comprising acontrol module.